1. Field of the Invention
The present invention relates to an inverter protection device, and particularly, to an inverter protection device capable of preventing malfunctioning thereof due to noise.
2. Description of the Related Art
Recently, due to general increases in power usage, there is concern about electrical power reserve rates, and thus, demand for high efficiency devices has gradually increased. Particularly, as demand on electricity supplies by devices such as air-conditioners or the like has rapidly increased over time, there is concern that demand for power may outstrip amounts of power able to be supplied. Further, recognition of the above-mentioned concern has been widespread both domestically and internationally.
Therefore, governments have introduced government subsidy programs according to efficiency grades of three major appliances. In addition, manufacturers of the major appliances have employed various technologies in order to develop and produce products coinciding with government energy efficiency policies. For example, a method of operating a motor driving circuit according to the related art has evolved to a pulse width modulation (PWM) motor controlling method employing an inverter, such that products having improved energy efficiency have been widely produced.
An inverter may refer to all devices converting direct current into alternating current. For example, an inverter may be used in a device for controlling and driving a motor.
According to the related art, inverters have been configured by using switching elements such as an insulated gate bipolar transistor (IGBT), a metal-oxide-semiconductor field-effect transistor (MOSFET) and a gate driver as separate unit elements. However, since a degree of integration of a circuit and a package has been improved at present, a single package in which all separate unit elements are integrated has been used.
An inverter module may drive and control a motor using a PWM signal. Further, an inverter module may monitor current flowing within each switching element. Based on the monitored currents, it may be determined as to whether a duty ratio of the PWM signal should be increased or decreased.
Meanwhile, in order to detect the current flowing in the switching element included in the inverter module, a current detection resistor (a shunt resistor) provided between the switching element and a ground at a low side of the inverter is commonly used. Based on voltage applied to both ends of the current detection resistor and reference voltage, an overcurrent state may be determined and destruction of the switching element may be prevented.
Meanwhile, when switching noise, lightning surge voltage from the outside, static electricity, or the like are applied to a circuit, a configuration in which the inverter circuit is protected and malfunctioning does not occur has been demanded.
Patent Document 1 described in the following related art document relates to an overcurrent detection circuit of an inverter, but fails to disclose a configuration for protecting against malfunctioning due to lightning surge voltage from the outside, static electricity, and the like.